Studies of High β Plasma Regions

Abstract:

Since its launch in August 2012, the Radiation Belt Storm Probe Ion Composition Experiment (RBSPICE) instrument on the NASA Van Allen Probes spacecraft have been making continuous high resolution measurements of Earth’s ring current plasmas. After a full traversal through all magnetic local times, a climatology of high β plasma events in the magnetosphere has been constructed. We outline these occurrences, their duration, and their general characteristics. We show that most high β events are associated with night-and-dusk-side injections and can last from minutes to hours, depending on the nature and cause of the injection. Most of these events have β < 2, with a few observations having β > 7. Other observations of particular note are high β events during quiet-time solar wind activity. We present a number of high β injection examples for both active and quiet times. Additionally, we present examples of high β plasma with and without associated magnetospheric wave generation. Given the high level of instrumentation on the Van Allen Probes, we are able to characterize injection events with unprecedented detail, potentially supporting new discoveries in fundamental plasma physics.